1. Field of the Invention
The present invention relates to a winding operation control method and apparatus for an automatic winder provided with rows of a multitude of spindles of a winding unit for taking up the yarn to produce a package.
2. Prior Art
A yarn supply bobbin produced at a fine spinning frame such as a ring spinning frame is supplied to an automatic winder of the following process, where the yarn is unwound, being taken up onto a package to a specific amount of yarn and a specific shape while yarn faults are removed. Usually several to scores of yarn supply bobbins are used to produce one package. In this automatic winder winding units having a multitude of spindles are arranged in parallel. Hereinafter the arrangement of one winding unit U will be explained by referring to FIG. 5.
In FIG. 5, the yarn Y unwound from a yarn supply bobbin 1 flows through a balloon breaker 2, an optical feeler 3 for detecting the presence or absence of the yarn Y, a disc-type tensioning device 5 for manual adjustment, and a yarn fault detecting head for checking and cutting off a yarn fault at a clearer 6, being taken up onto a package P rotating on a traverse drum 7. This package P is rotatably supported on a cradle 9 at both ends of its taken-up tube 8. Provided on the large-diameter side of the cradle 9 is a friction roller 10 which is slightly larger in diameter than the large-diameter end of the take-up tube 8; at the initial period of winding on the package P the friction roller 10 and the drum 7 rotate in contact with each other, taking up the yarn Y.
A yarn signal from the clearer 6 is inputted into a unit controller 11. The unit controller 11 is designed to cut off and remove a faulty yarn by the cutter built in the clearer 6 upon finding out the faulty yarn such as a slub, thick yarn and thin yarn. Thereafter, the suction mouth 13 is rotated to the package P side and at the same time the drum 7 is rotated reversely to catch the upper yarn, then rotating the suction mouth 13 downwardly in the drawing to guide the upper yarn to the yarn joining device 15. Also an intermediate joining pipe 14 is rotated to the vicinity of the feeler 3 to catch the lower yarn running to the feeler 3; then the intermediate joining pipe 14 is rotated upwardly in the drawing to guide the lower yarn to the yarn joining device 15. Then, after the upper and lower yarns are joined at the yarn joining device 15, the drum 7 is rotated to restart winding.
A motor 16 which drives the drum 7 is controlled by the unit controller 11. The rotation of the drum 7 is detected by a drum rotation sensor 17, which produces pulse signals which are counted and integrated by the unit controller 11. An integrated value thus gained is compared with a set value by a control device 18 which controls the winding unit U of a multitude of spindles. When the package has been wound to a specific yarn length, the drum 7 is stopped and the green lamp 19 is turned on, indicating that the bobbins are waiting for doffing by a doffing device.
The feeler 3 functions to detect the absence of the yarn, outputting a no-yarn signal to the unit controller 11. When the bobbin 1 has been fully unwound, the feeler 3 outputs the no-yarn signal and at the same time the clearer 6 which detects a yarn defect stops outputting a yarn signal. With the detection of the empty bobbin, the unit controller 11 outputs a "bobbin change" command; the empty bobbin is thus discharged and a new bobbin 1 is fed to the winding position. The yarn end found out from the new bobbin 1 is blown upwardly to the vicinity of the feeler 3, being joined at the yarn joining device 15 by the operation of the above-described suction mouth 13 and the intermediate joining pipe 14. Subsequently the unwinding of the bobbin 1 is started.
In each winding unit, usually several to several tens of supply bobbins 1 are joined while being removed of their yarn defects, forming one full package. Production performance of this winding unit U largely depends upon the winding speed, but the practical winding speed of a prior-art winding unit U was around 1000 m/min. because the unwinding tension increased with an increase in the winding speed. Particularly from the time when the bobbin has been unwound 70 percent, that is, when about 30 percent of yarn remains on the bobbin, the mean angle of separation of a yarn from the yarn layer of the bobbin 1 decreases, resulting in friction between yarns or friction between the yarn and the take-up tube and sudden increase in the unwinding tension which causes the occurrence of yarn breakage due to the tension.
In an attempt to prevent such an increase in the unwinding tension, there has been proposed such an automatic winder that can offset an increase in the unwinding tension of the yarn by supervising the unwinding tension by the yarn tension detecting device and by gradually reducing the yarn tension being added by the tensioning device which is adjustable.
However, the winding unit U is provided with equipment along the yarn path and there exists almost no excess space for newly setting up a yarn tension detecting device. Besides, the tension detecting device is comparatively expensive and therefore it is impossible to set it for every winding unit U. It is, therefore, considered to output a desired tension pattern to the variably controllable tensioning device 5 of each winding unit U from the control device which controls the winding unit U, without providing the tension detecting device. However, there exists such a problem that since the tension adjusting effect of the tensioning device varies with the type of yarn to be handled, it is unknown whether the yarn tension is gradually decreased for the purpose of actually offsetting an increased unwinding tension when a tension pattern one-sidely set by the control device 18 is used.
In view of the above-described problems, the present invention has been accomplished and has an object to provide a tension control device of an automatic winder capable of increasing and decreasing the yarn tension to a desired value without using a tension detecting device at each winding unit.